To assess the safety, tolerability, immunogenicity and efficacy of the CAIV-T vaccine to protect childen receiving either a one-or two-dose primary vaccination against culture-confirmed influenza illness caused by subtypes antigenically similar to those contained in the vaccine or placebo (whether the subject received a one-or-two-dose primary vaccination regimen) and the end of the subsequent influenza season. This study has completed recruitment and we are waiting for sampling and the end of influenza season.